Pyrolytic conversion of hydrocarbons



Aug. l, 1950 R. B; SMITH PYRoLYTIc CONVERSION oF HYnRocARBoNs.

Filed April 29. 1947 xml-COQ n INVENToR READING BARLOW SMITH ATTORNEYSPatented Aug. 1, 1950 ATENT OFFICE rYRoLYTIc CONVERSION. or

HYDROCARBONS Reading Barlow Smith, Hammond, Ind., assigner to SinclairRefining Company', NewYork, N. Y., a corporation of MaineYApplicatiqnnpril 29, 194i, serial No.Y 744,659

This invention relates ofthe pyrolytic con'- version' of hydrocarbonsand, more particularly; to pyrolytic conversionprocesses involving theuse of'a nely divided catalyst.

The invention is especially applicable to con` version processes of thegenerall type wherein a finely divided catalyst, at elevated'temperature, is suspended in oil vapors, passed to a reaction zone inwhich conversion ofthe oil occurs and which spent catalyst is separatedfrom the oil vapors, the separated catalyst stripped* of oil,regenerated by burning off `colte' or carbon deposited thereon,f and theregenerated catalyst again suspended in: the stream` of oil vaporspassing to the reaction zone. Operations of the type described. arecommonly designated fluid' catalyst processes.A

`In conventional operation,` the. spent catalyst normally passes fromthe bottom oi the reactor tlno'ughv a stripping column extending:downwardly from the lower end of` the'reactor` andrin which the`catalyst is contacted withv steam forthe purpose of removing, orstripping, from the catalyst vaporizable hydrocarbons `remainingthereon. The stripped catalyst passes from the bottoni of the stripperand is picked up by a stream of air and conveyed thereby into'`thefbottom of the regenerator in which the" catalyst, at elevatedterriperasture,` is intimately contacted with air, or other oxidizinggases, whereby carbonaceous de` posits` are burned off and theregenerated cata-` lyst is Withdrawn from the regenerating zone andreturned 'tc-v the reactor. 1 r,

\ Flue gases, products 'of the co' bustion,` pass from the 'top-of theregenerator to astack; or: precipitator,` for' the recovery otcatalystfines from the gases.

The soecalled catalyst fines are'scomposed of extremely finely divided`particles of the solid;

catalyst, some of which may be present in` the My present invention pr'des an improved process 'adapted to continuous operation andYcomprising aI plurality' of cooperating steps so coordinated as toconstitute a: unitary operation in` which-a: charge: of4 catalyst isArepeatedlyusedand intermittently regenerated and returned to theconversion zone and in which catalyst iines are' effectively recoveredand returned to the system.

In accordance with my present invention, the eluent gases from theregenerating zone, with the catalystV ii-nes suspended therein, aresubjected tol ultra-sonic vibrations of the order of about one-halfmegacycle per second whereby the' particles of finely divided catalystdispersed in the eflluent gases are caused to coagulate or agglomerateto such an extent that theyv are readily separable from the eiuentgases, for instance, by settling. The' ultra-sonic vibrations may begenerated in the known manner by high frequency electrical excitation ofa piezoelectric crystal, for instance, a piezoquartz crystal.

These vibrations may, with advantage, be imparted' to the gaseoussuspension by passing the suspension through a chamber in contact with adiaphragm adapted to be vibrate'd at the previously noted ultra-sonicfrequency, for instance', a diaphragm such as described separating thechamber from an adjacent cooled chamber containing a vibrating' crystalsubmerged in a cooling liquid; From the rst said chamber, the gaseoussuspension may be passed to an enlarged settling chamber in whichagglomerates of the catalyst nes are' separated by gravity settling andfrom which the separated fines are: returned to the reaction chamber.Other conventional means for separating the agglomerates from the gasesmay be employed.

The invention Will be further described and illustrated with referenceto the accompanying drawing which represents conventionally and somewhatdiagrammatically a flow diagram of a uid catalyst cracking operationembodying my invention.

Referring more particularly to the embodiment of theinvention showninthe drawings, the apparatus indicated by thee lreference numeral lrepresents a generally cylindrical reactor of conventioral type.` "I-h'efinely divided catalyst suspended'inl oil' vapors, enters the reactorthrough conduitl 2l extending into the reactor, and ter-` minating vaconical member 3 of `somewhat smaller maximum diameter than the reactorand opening upwardly into the reactor through a conventionalgridynotshown. v

As the hot vapors pass upwardly through the reactor, there is aitendency for the catalyst to drop out of suspension forming aso-called.- densef'phaseyor high density, body of cata lyst in thereactor from whiclrthecatalyst flows Aand connections 24 and 25.

also serves as a medium for transmitting the 4 A While I have forsimplicity shown a single vibrating diaphragm in the chamber I1, it willbe understood that a plurality of such diaphragms may be employed. It isgenerally desirable to impart to the suspension passing through chamberI1 vibratory energy equivalent to about 250 acoustical watts` per 'cubicfoot of volume of the chamber.'

It will be understood that the utility of the .present invention is notrestricted to the particu- -lar embodiment thereof herein described, butis f `applicable to various modifications of fluid and passes downwardlytherethrough in contact v with steam or other gaseous stripping mediumintroduced into the bottom` of lthev stripperthrough line 1, strippedcatalyst passes from catalyst processes in which catalyst nes arecarried off in suspension in eiliuent regenerator the bottom of thestripper through conduit 8,.,

in which there is interposed a valve' 9, and ilows into conduit I0 whereit is picked up bya cur'- E rent of air or other oxidizing gas andcarried upwardly into the regenerator II. In the regenerator,carbonaceous deposits are burned Voff from the catalyst by contact withthe air, or other oxidizing gas, introduced through conduit I0, theproducts of combustion passing from the upper portion of the regeneratorthrough cyclone separator I2, for the separation of the larger particlesof suspended catalyst, and from which the products of combustion passthrough conduit I 3, the separated catalyst being returned to the densephase body of catalyst in the regenerator.

Regenerated catalyst is withdrawn from the bottom of the regeneratorfrom a Zone above the grid It through regenerated catalyst leg I5, inwhich there is interposed valve IB, advantageously a conventional slidevalve, for the control of the flow of catalyst therethrough into thelower end of conduit 2 where it is picked up by a stream of preheatedcharge oil passing to the reactor.

. Flue gases, passing from the regenerator through conduit I3 andcarrying catalyst fines in suspension, are passed through chamber I'Ivin` which they are subjected to ultra-sonic vibration transmitted to thesuspension through diaphragm I8 forming a partition between chamber IIand the continuous chamber I9 lin which there is a piezo-crystal adaptedto be excited, in the conventional manner, by high frequency electricalimpulses transmitted to the crystal through electrical connections and 2I The crystal is protected from temperature rise due to heat transmittedthrough the, diaphragm by continuously circulating a liquid coolingmedium, oil, for instance, through the chamberk I9, by means of pump 22,cooler 23 The cooling liquid vibrations of the crystal to the diaphragm.Flue gases, together with agglomerates of catalyst lines, pass fromchamber I'I through conduit 26 to enlarged settling chamber 2l, fromwhich the flue gases pass through conduit 2B to a stack, not shown, andseparated catalystpasses through conduit 29 into elevator conduit 30wherein'it is picked up by a current of aeration air and carried up intostorage bin 3| from which it flows, in a fluidized state, through leg-32 into the lower end of conduit 2 where'it is picked'up by the currentof hydrocarbon charge oil and carried into the reactor, together withcatalyst from the regenerator. The flow of catalyst through the leg 32is regulated and controlled by valve 33. l l

gases.

The catalystemployed may be of the type conventionallyv used in fluidcatalyst processes, for instance, a silica-alumina type catalyst infinely dividedv or powdered form. The reaction conditions may likewisebe those conventionally used in `operations of this type and, asunderstood by the art, the optimum temperatures and pressures employedwill depend primarily upon the type of feed stock used, thevparticular.catalyst employed, and the reaction desired.

; Incrackinggas oil, for instance, the reaction temperature may, withadvantage, be Within the range of 800 to 1,000 F. and the pressure atthe top of the reactor within the range'of about 5 to 25 pounds persquare inch. The regeneration temperature may be kwithin the range of950 to 1,200 F., heat for the reaction being supplied in large measureby the hot catalyst passing into the charge oil from the regenerator.

The invention is 'not restricted to the particular means shown forgenerating the ultra-sonic vibrations or imparting the vibrations to thesuspensions but contemplates other known means for imparting energy inthe Vform of ultra-sonic vibrations to the respective suspensions.Further, ultra-sonic vibrations varying somewhat from the .specificfrequency given maybe used without departing from the spirit of theinvention and may be more or less effective in coagulating catalystlines of some types.

`I. In the 'uid catalyst process for the conversion vof hydrocarbons inwhich a linely divided catalyst is repeatedly used and intermittentlyregenerated in a regenerating zone by burning oi the carbonaceousmaterial deposited thereon and catalyst fines'are carried oII insuspension in the combustion gases from the regenerating zone, the

step' of recovering catalyst nes from the suspension-by subjecting? thesuspension to ultra-sonicv vibrations of the order of one-half megacycleper second, whereby the catalyst fines are agglomcatalyst is repeatedlyused and intermittently re.

generated ina regenerating zone by burning oII the carbonaceous materialdeposited thereon vand catalystnes arecarried olf in suspension in thecombustion gases from the regenerating zone, thel stepfofrecoveringcatalytic l'lnes from the suspension which comprises passingthe suspension.

through-a vconiined zone and subjecting the suspension therein toultra-sonic vibration of ay frequency of'theorder of one-half megacycleperv second vand ofi an `intensity equivalent to 250 acoustical'fwattspercubic foot, whereby :the

5 catalyst fines are agglomerated, separating the agglomeraties ofcatalyst fines from the gases and returning the separated catalyst finesas separated from the suspension to the zone of hydrocarbon conversion.`

READING BARLOW SMITI'H.

REFERENCES CITED The following references are of record in the le ofthis patent:

6 UNITED STATES PATENTS OTHER REFERENCES Bergmann, U1tras0nics, pp.212-216, John lo Wiley and Sons (1938).

1. IN THE FLUID CATALYST PROCESS FOR THE CONVERSION OF HYDROCARBONS INWHICH A FINELY DIVIDED CATALYST IS REPEATEDLY USED AND INTERMITTENTLYREGENERATED IN A REGENERATING ZONE BY BURNING OFF THE CARBONACEOUSMATERIAL DEPOSITED THEREON AND CATALYST FINES ARE CARRIED OFF INSUSPENSION IN THE COMBUSTION GASES FROM THE REGENERATING ZONE, THE STEPOF RECOVERING CATALYST FINES FROM THE SUSPENSION BY SUBJECTING THESUSPENSION TO ULTRA-SONIC